Patent GB-594558-A (GB)
Title: Improvements in the manufacture of intermediates and photographic sensitising dyes made therefrom
IPC: C09B23/02
Filed: 1945-03-01
Abstract: Dye intermediates of the general formula <FORM:0594558/IV/1> (wherein Q represents a sulphur or selenium atom, R a substituted or unsubstituted 2-furyl group, R1 a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, substituted (e.g. p-chlorophenyl) or unsubstituted, and R2 a substituted or unsubstituted amino group or (when Q is sulphur) an alkylthio or aralkylthio group) are manufactured by heating a thiourea or a selenourea or an S-alkyl- or S-aralkyldithiocarbamate with a 2-furyl halogenomethyl ketone of the general formula <FORM:0594558/IV/2> advantageously in a solvent such as methyl, ethyl, n-propyl, isopropyl, n-butyl or isobutyl alcohol, and in the presence of alkalis, e.g. alkali metal carbonate or bicarbonate.  Specified sulphur or selenium compounds are thiourea, selenourea, methylthiourea, phenylthiourea, benzylthiourea, methyl, ethyl, n-propyl, isobutyl dithiocarbamates or benzyl dithiocarbamate. Specified halogenated ketones are 2-chloracetyl-, 2-bromoacetyl-, 2-iodoacetyl-, 2-(a  - chloropropionyl)-, 2 - (phenylchloracetyl)-and 2 - (a  - chloro b  - phenylpropionyl) - furan.  The resulting thiazole or selenazole derivatives may be quaternated by heating with alkyl or aralkyl esters of inorganic acids or of arylsulphonic acids, e.g. alkyl halides such as ethyl and n-propyl iodide, n-propyl, isobutyl or n-butyl bromide or n-butyl chloride, alkyl arylsulphonates such as ethyl p-toluenesulphonate or methyl benzenesulphonate, aralkyl halides such as benzyl bromide or chloride, or dialkyl sulphates such as dimethyl or diethyl sulphate. The anion of the resulting salts may be changed and a less soluble quaternary salt produced by treating an alcoholic or aqueous solution of the more soluble quaternary salt with an aqueous metal salt; e.g. the quaternary iodides, bromides, perchlorates as rhodanates may be obtained by the action of the corresponding sodium or potassium salts on the quaternary chlorides, p-toluene sulphonates or alkylsulphates. Methine or polymethine dyes are obtained by treating an intermediate of the general formula above, or its quaternation-product, wherein in either case Q represents a sulphur atom and R2 an alkylthio or aralkylthio group, by any known method for converting a heterocyclic nitrogen base or its quaternary salt having such group in the a -position to the nitrogen atom into methine or polymethine dyes; e.g. by condensing a quaternary salt of the type described with a cyclammonium quaternary salt having a methyl group in the a - or g -position to the quaternary nitrogen atom to produce a monomethine cyanine dye of the general formula <FORM:0594558/IV/3> (wherein n is 0 or 1, R3 and R6 each represents an alkyl or aralkyl group, X an anion and Z1 the non-metallic atoms necessary to complete a substituted or unsubstituted heterocyclic nucleus, e.g. the nucleus of thiazole, 4-methyl-, -phenyl- or -(21-thienyl)-thiazole, benzthiazole, 5-chlorobenzthiazole a - or b -naphthathiazole, 4-methyl- or -phenyl-oxazole, benzoxazole, 5-phenylbenzoxazole, a - or b -naphthoxazole, 4-methyl- or -phenyl-selenazole, benzselenazole, a - or b -naphthaselenazole, thiazolines, quinoline, 6 : 7 - dimethylquinoline or 3 : 3 - dimethylindolenine); or with a ketomethylene heterocyclic compound containing in the ring the grouping <FORM:0594558/IV/4> (wherein A represents an oxygen or sulphur atom, a carbonyl or an -NR4- group, R4 representing hydrogen, alkyl, aralkyl or aryl) to produce a merocyanine dye of the general formula <FORM:0594558/IV/5> (wherein R3 represents an alkyl or aralkyl group and Z the non-metallic atoms necessary to complete a substituted or unsubstituted heterocyclic nucleus, e.g. of rhodanine, 2-thio-2 : 4-oxazoledione, 2-thiohydantoin, 2-diarylamino -4- ketothiazolines, 2 - (N - alkyl - N - arylamino)-4-ketothiazolines or thiobarbituric acid).  The condensations are advantageously effected in presence of an acid-binding agent, e.g. a tertiary amine such as trialkylamine (e.g. triethyl-, tripropyl- or tributyl-amine) or an alkali metal carbonate (e.g. sodium or potassium carbonate), conveniently in a solvent, e.g. an alcohol such as ethyl, n-propyl or isopropyl alcohol.  In examples: (1) thiourea, 2-chloroacetylfuran and ethanol are heated together with addition of anhydrous sodium carbonate to produce 2-amino-4-(21-furyl)-thioazole; (2) methyl dithiocarbamate, 2-bromoacetylfuran and ethanol are warmed together to precipitate the hydrobromide of 2-methylthio-4-(21-furyl)-thiazole, from which the free base is isolated by adding aqueous sodium carbonate to the ethanolic solution; similarly, 2-butylthio-, 2 - benzylthio- and 2 - ethylthio - 4 - (21 - furyl) -thiazole are prepared using butyl, benzyl and ethyl dithiocarbamates respectively; (3) 2-methylthio-4-(21-furyl) - thiazole methiodide is obtained by heating together 2-methylthio-4-(21-furyl)-thiazole and methyl p-toluenesulphonate, diluting the melt with spirit and pouring into aqueous potassium iodide; (4) 2 - methylthio - 4 - (21-furyl) - thiazole and ethyl p-toluenesulphonate are heated together to form 4 - (21 - furyl) - 2 - methylthiothiazole etho - p -toluenesulphonate; (5) 2 - methylthio - 4 - (21 - furyl) - thiazole methiodide, 3 - ethylrhodanine, triethylamine and ethanol are boiled together to produce [5 - (3 - ethylrhodanine)] - (2 -{4 - (21-furyl) - 3 - methyl - thiazole}] - merocyanine; (6) 2 - methylthio - 4 - (21 - furyl) - thiazole etho - p -toluenesulphonate, 2 - diphenylamino - 4 - keto -thiazoline, triethylamine and ethanol are boiled together to isolate [5-(2-diphenylamino-4-ketothiazoline)] - [2-{4 - (21-furyl) - 3 - ethylthiazole}]-merocyanine; (7)-(15) other merocyanine dyes can similarly be obtained by reaction of 2 - methylthio - 4 - (21 - furyl) - thiazole etho - p -toluenesulphonate with 3-phenylrhodanine, 3-ethyl - 2 : 4 - oxazoledione, 1 : 3 - diphenyl - 2 -thiohydantoin or 1 - ethyl - 3 - phenyl - 2 - thiohydantoin, or of 2-methylthio-4-(21-furyl)-thiazole methiodide with 3-(b -hydroxyethyl)-rhodanine, 2-thiohydantion, rhodanine, thiobarbituric acid or 2-(N-ethyl-N-phenyl)-amino-4 - ketothiazoline.  Cyclammonium quaternary salts containing a reactive methyl group and suitable for producing monomethine cyanine dyes include 2-methylbenz-thiazole, -selenazole and -oxazole ethiodides, 2-methyl-b -naphthathiazole metho-p-toluenesulphonate, 2-methyl-a  - naphthathiazole etho - p - toluenesulphonate, quinaldine and lepidine ethiodides, 2-methyl-4-(21-furyl)-thiazole methiodide and 2-methyl-4-(21-pyrryl) - thiazole quaternary salts. Specifications 537,961, 571,077 and 594,559 are referred to.  2-Methyl-4-(21-furyl)-thiazole methiodide is obtained by heating together 2-methyl-4-(21-furyl)-thiazole and methyl p-toluenesulphonate and treating the product with aqueous potassium iodide.  2-Methyl-4-(21-furyl)-thiazole is obtained by warming together thioacetamide, 2-bromoacetyl-furan and ethanol, and treating the resulting hydrobromide with aqueous sodium carbonate. 2-Chloroacetylfuran is obtained by treating furoyl chloride with an ethereal solution of diazomethane and treating the resulting 2-diazoacetyl-furan with dry hydrogen chloride.  2-Bromoacetylfuran is obtained as above using dry hydrogen bromide.